Formation mechanism and stability of austenitic islands in carbides in a Ni-Cr-Fe based high-temperature austenitic alloy undergoing carburization

Shipeng Shu*, Xiaobing Hu, Maryam Kazemzadeh-Atoufi, Tao Liu, Anyu Shang, Mark B. Davis, Robin Ziebarth, Sandeep Dhingra, Robert D. Morgan, Yao Du, Peter W. Voorhees, David N. Seidman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate a phase transformation in a Ni-Cr-Fe-based high-temperature alloy during the technologically important carburization process, with multi-length scale experimental techniques. The study focuses on the formation and stability of novel austenitic islands formed within carbide structures during the M23C6 to M7C3 phase-transformation. We demonstrate that the austenitic islands nucleate near the M23C6/M7C3 transformation front, from a supersaturation of metal atoms in the M23C6-carbide as M7C3 grows. After formation, the austenitic islands equilibrate their composition with the matrix temporally but remain relatively stable inside the carbides due to their large sizes (a few hundred nanometers in diameter) and a weak Gibbs-Thomson effect.

Original languageEnglish (US)
Article number113792
JournalScripta Materialia
Volume197
DOIs
StatePublished - May 2021

Keywords

  • Analytical electron microscopy
  • Atom-probe tomography
  • Dual-beam FIB tomography
  • High-temperature alloys
  • Phase transformation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

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